The present invention relates to hydraulic clutch release mechanisms which can be utilized in the power trains or drive trains of motor vehicles to transfer clutch pedal action to the fork or release bearing of the clutch. As disclosed, for example, in "Modern Automotive Technology", authored by James E. Duffy and published by the Goodheart-Willcox Company, Inc., Tinley Park, Ill., a hydraulic clutch release mechanism normally comprises three basic parts, namely, a clutch master cylinder (also called clutch cylinder), a hydraulic line and a slave cylinder.
A hydraulic clutch release mechanism replaces earlier types of clutch release mechanisms including those wherein a Bowden wire is employed to transmit motion from the clutch pedal to the release member (such as a fork) for a friction clutch. Depression of the clutch pedal, which is operatively connected with a clutch release member by a hydraulic release mechanism, entails the actuation of the master cylinder (the pressure of hydraulic fluid in the plenum chamber of the master cylinder rises), and the piston of the master cylinder expels pressurized hydraulic fluid, by way of the hydraulic line, into the plenum chamber of the slave cylinder. The piston of the slave cylinder is caused to perform a stroke which results in disengagement of the clutch by way of the aforementioned clutch release member.
A drawback of presently known hydraulic clutch release mechanisms is that the installing of the hydraulic line, the installing of various connections between the hydraulic line and at least one of the cylinders, and the installing of fluid-conveying connections between the cylinders, are time-consuming procedures primarily due to lack of space under the hood of a motor vehicle. Moreover, a hydraulic line cannot be bent to any desired extent, and this also contributes to the space requirements of conventional hydraulic clutch release mechanisms, not only in fully assembled and installed condition of the release mechanism but also (and often especially) during mounting of conventional release mechanisms in the power trains of motor vehicles. Heretofore known proposals to cope with the above outlined problems include the utilization of specially designed elbows, adapters, tees and analogous complex, costly and often bulky components.
U.S. Pat. No. 4,601,374 (granted Jul. 22, 1986 to Ladin for "HYDRAULIC CLUTCH PISTON AND SEAL") discloses a hydraulic clutch release mechanism which comprises the above-enumerated constituents; however, the patentee is not concerned with and does not discuss the manner of assembling the constituents and of installing them in a motor vehicle. The connection between the master and slave cylinders comprises a threaded joint. The hydraulic line between the two cylinders has an end portion extending radially of the housing of one of the cylinders, and an arcuate second portion adjacent the end portion. The space requirements of the just described hydraulic line are quite pronounced so that such clutch release mechanisms cannot be put to use in numerous types of vehicles, especially those embodying front wheel drives. Moreover, the mounting of such mechanisms in those vehicles which provide adequate space to accommodate a hydraulic line with the aforedescribed radially extending and arcuate sections is a complex and time-consuming operation.
U.S. Pat. No. 5,108,135 (granted Apr. 28, 1992 to Mercado for "FIBER REINFORCED PLASTIC PIPE TEE") discloses a fitting which can be put to use in certain types of hydraulic clutch release mechanisms. However, this patent fails to disclose any solutions how to approach the problems which arise in connection with the assembly of the constituents of a clutch release mechanism and/or in connection with the installation of an at least partially assembled release mechanism in a motor vehicle.
U.S. Pat. No. 5,113,657 (granted May 19, 1992 for "MODULAR HYDRAULIC CONTROL APPARATUS" to Compton et al.) discloses a hydraulic release mechanism employing modular quick-connect members which include one-way locking arrangements. This patent also fails to offer effective and generally useful solutions of the aforediscussed problems arising in connection with the utilization of conventional hydraulic clutch release mechanisms.
The disclosures of our German priority application Serial No. 197 54 702.8 (filed Dec. 12, 1997) and of all U.S. and foreign patents and patent applications identified in the specification of the present application are incorporated herein by reference.